Cam systems

ABSTRACT

A cam system enable speed and power generation of a mechanical activity, effected by operation of the cam, to be varyingly adjusted. Cam structures, a cam follower, and a movable cam shaft are used to effect operation of the cam system. A central cam structure receives the cam shaft and move therewith. A side cam structure is positionally varied with respect to the central cam structure for changing the profile of the central cam structure alone and in turn changing in the overall profile followed by the cam follower during movement of the cam shaft and any cam structures related thereto. Changes in profile effected by the positional configuration of the side cam structures effecting variable translational motion to the cam follower during movement of the central cam shaft and cam structures, which enable variation in speed or power of operation of a preferred movement relevant to a mechanical requirement.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention is directed to improvements in and relating to cam systems. In particular, the invention relates to aspects of the manufacture and operation of an improved cam system incorporating features to enable the speed of the cam to be varyingly adjusted in several ways.

[0003] 2. Description of the Related Art

[0004] It is envisaged the adjustable cam will be used with traveling irrigators. However, it should be appreciated that this invention may have applications outside this field.

[0005] The cam is one of the most basic means of timing or activating interrelated motions. A cam is a mechanical component on which a particular profile has been machined. The profile of the cam effects a follower to move in a particular way. More particularly, a shaft (typically associated with the cam) is rotatable. As the cam shaft rotates, so does the cam with which it is associated. As the cam rotates, a follower effects a preferred movement relevant to an inter-related mechanical requirement.

[0006] While the present invention has a number of potentially realizable applications, it is in relation to problems associated with existing cam systems used with traveling irrigators that the present invention was developed. More specifically, it was with the problems associated with the lack of ability to vary the cam speed within readily available variable systems, or within existing fixed cam structures in mind, that the present invention was developed.

[0007] Travelling irrigators are commonly used on farms for transferring the substantially liquid wastes from a dairy (milking) shed over neighboring paddocks in a manner that directly returns raw nutrients to the land. The traveling irrigator includes a rotating boom which as the boom rotates effectively sprays the fluid nutrients out over the surface adjacent to and over which the irrigator travels. The irrigator “travels” in a unidirectional way due to the winding in of a wire rope associated with the irrigator. While dairy shed wastes may be sprayed over farm land via such an implement, in other applications any suitably fluid substance may be sprayed, or aerated, as required for the particular situation.

[0008] The cam associated with a traveling irrigator is typically in the form of a plate cam. In such machinery the cam system provides power to wind in the wire rope of the traveling irrigator during revolution of the cam plate and as the irrigation boom revolves. The rotational movement of the cam plate is translated through the cam follower to effect the winding in of the wire rope of the irrigator. Thus, the irrigator travels across an area at a speed in response to the speed at which the wire rope being wound in. In such applications the cam plate is limited to a fixed preferable size and shape. Such fixed structural features operate against the cam dimensions being adjustable and thus limit adjustability of the translational motion effected through the follower and hence restricts any variability of the speed of the preferred operation, being the speed of travel of the irrigator as dictated by the speed of winding in of the wire rope of the irrigator.

[0009] There is a range of fixed cam systems available in the prior art. Adjustable cam systems are also known, (such as use of time adjustable cam gears to enable an engine's cam timing to match its tuning state). However, existing adjustable speed cams are not preferably transferable to the operation of a traveling irrigator.

[0010] Having a simple variable speed cam system for use with traveling irrigators would benefit the operation of the irrigation process by allowing for either a speeding up of the operation or slowing it down, depending on the size of the area being irrigated and/or the quantity of fluid being delivered by the irrigator.

[0011] However, at times it is useful to have the standard cam plate to effect the standard operation of the machine.

[0012] It would be useful therefore, to have a cam system that:

[0013] a) could have the benefits of being adapted to vary the cam speed to increase or slow the speed of the particular operation when required; yet

[0014] b) could operate at a standard fixed speed relevant to the machine and requirements of the situation in certain circumstances; and

[0015] c) could be easily adjusted requiring minimum time and physical requirements on the part of the user; and

[0016] d) offered a range of adjustments to effect incremental speed adjustment.

[0017] It would therefore be advantageous to have an invention that offered at least some if not all of the advantages of the above proposed system.

BRIEF SUMMARY OF THE INVENTION

[0018] It is therefore an object of the present invention to consider the above problems and provide at least one solution which addresses a plurality of these problems.

[0019] Ideally the present invention will also provide a cam system which allows for the substantially trouble free variability of cam speed.

[0020] Ideally the cam system is suitable for use or is suitable to being adapted for use in situations where fixed speed cams are currently employed.

[0021] It is therefore a further object of the present invention to at least provide the public with a useful choice or alternative system.

[0022] Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only. It should be appreciated that variations to the described embodiments are possible and would fall within the scope of the present invention.

[0023] While the present invention has particular reference to the features and use of a plate cam, it should be appreciated that the invention may also be applicable to and/or be adapted for use with a face cam, or a cylindrical (drum) cam in particular circumstances.

[0024] For the purposes of this specification a plate cam shall mean and include any flat substantially disc shaped structure or plate having a preferred shape (or profile) machined on to the edge of it. The follower is placed in contact with this edge profile and as the cam is rotated in conjunction with the associated rotating (cam) shaft, the edge profile translates into a particular movement of the follower, such as an up and down vertical movement, or in and out lateral movement.

[0025] Also, for the purposes of this specification, a face cam shall mean and include any substantially disc shaped structure which includes on at least one of its faces a groove machined therein. The follower follows the groove as the cam rotates.

[0026] Similarly, a cylindrical or drum cam shall mean and include any cylinder of appropriate dimensions which has a profile machined into it, such that as the cam rotates the profile effects a particular motion with respect to the follower.

[0027] As can be appreciated, there are a range of followers available for use with the varying cam structures. These include knife-edge, roller and/or flat followers.

[0028] With reference to the present invention, the cam herein described has preferable application with either or both a knife edge and roller follower. However, more typically a roller follower is most often used on traveling irrigators of the kind discussed with relevance to the present description.

[0029] According to one aspect of the present invention, there is provided a cam system, the cam system including at least two cam structures, a cam follower capable of following a preferred profile effected by the configuration of at least one of the cam structures, and a substantially central rotatable cam shaft, the two cam structures comprising at least one central cam structure and at least one side cam structure, the central cam structure being adapted to receive the cam shaft and further adapted to receive the at least one side cam structure, the side cam structure being adapted to be positionally varied with respect to the central cam structure thereby, in conjunction with the central cam structure, effecting a change in the profile of the central cam structure alone, and in turn effecting a change in the overall profile followed by the cam follower during rotation of the cam shaft and the cam structure(s) related thereto, the cam system characterized by the change in profile effected by the positional configuration of the side cam structure relative to the central cam structure, effecting variable translational motion to the cam follower and effecting in turn a variation in speed of operation of a preferred movement relevant to a mechanical requirement.

[0030] According to another aspect of the present invention, there is provided a method of manufacturing a cam system substantially as described above, the cam system including at least two cam structures, a cam follower capable of following a preferred profile effected by the configuration of at least one of the cam structures, and a substantially central cam shaft, the two cam structures comprising at least one central cam structure and at least one side cam structure, the central cam structure being adapted to receive the cam shaft and further adapted to receive the at least one side cam structure, the side cam structure being adapted to be positionally varied with respect to the central cam structure thereby effecting a change in the profile of the central cam structure alone, and in turn effecting a change in the overall profile followed by the cam follower during rotation of the cam shaft and the cam structure(s) related thereto, the cam system characterized by the change in profile effected by the positional configuration of the side cam structure effecting variable translational motion to the cam follower and effecting in turn a variation in speed of operation of a preferred movement relevant to a mechanical requirement.

[0031] According to another aspect of the present invention, there is provided a method of varying the speed of operation of a cam system substantially as described above, the cam system including at least two cam structures, a cam follower capable of following a preferred profile effected by the configuration of at least one of the cam structures, and a substantially central cam shaft, the two cam structures comprising at least one central cam structure and at least one side cam structure, the central cam structure being adapted to receive the cam shaft and further adapted to receive the at least one side cam structure, the side cam structure being adapted to be positionally varied with respect to the central cam structure thereby effecting a change in the profile of the central cam structure alone, and in turn effecting a change in the overall profile followed by the cam follower during rotation of the cam shaft and the cam structure(s) related thereto, the cam system characterized by the change in profile effected by the positional configuration of the side cam structure effecting variable translational motion to the cam follower and effecting in turn a variation in speed of operation of a preferred movement relevant to a mechanical requirement.

[0032] According to another aspect of the present invention, there is provided a cam system substantially as described above wherein the cam structure(s) comprises any one of a plate cam, a face cam, a drum cam relevant to the application with which the cam system is used.

[0033] According to another aspect of the present invention, there is provided a cam system substantially as described above wherein the follower comprises any one of a knife-edge follower, a roller follower.

[0034] According to another aspect of the present invention, there is provided a cam system substantially as described above wherein either or both the central cam structure and the side cam structure take any appropriate shape as required to effect a preferred edge profile as required to effect preferred translational motion via the follower to effect operation of a mechanical requirement.

[0035] According to another aspect of the present invention, there is provided a cam system substantially as described above wherein either or both multiple central cam structures and side cam structures may be employed.

[0036] According to another aspect of the present invention, there is provided a cam system substantially as described above wherein the number and arrangement of the side cam structure(s) relative to the central cam structure(s) determine desired variability in timing/speed of the translational motion of the follower to effect variability in the mechanical operation required.

[0037] According to another aspect of the present invention, there is provided a cam system substantially as described above wherein either or both the central cam structure(s) and the side cam structure(s) are maintained in a fixed relationship to each other during operation of the cam by the configuration of either or both cam pivoting apparatus and cam locking apparatus.

[0038] According to another aspect of the present invention, there is provided a cam system substantially as described above wherein in order to interlock the cam structures, each structure includes at least one aperture capable of alignment with a complementary aperture on another structure, through which the cam locking apparatus is engaged.

[0039] According to another aspect of the present invention, there is provided a cam system substantially as described above wherein the configuration of the cam locking apparatus complements the configuration of the apertures and includes any one or more of a tapered, threaded, bayonet, push fit locking pin.

[0040] According to another aspect of the present invention, there is provided a cam system substantially as described above wherein side cam structure is adjustable positionally with respect to the central cam structure.

[0041] According to another aspect of the present invention, there is provided a cam system substantially as described above wherein the cam system becomes adjustable via the use of complementarily positioned apertures on the cam plates.

[0042] According to another aspect of the present invention, there is provided a cam system substantially as described above wherein the positioning of the apertures on the cam plates, the distances between adjacent apertures and the ability to variably position the side cam structure(s) with respect to the central cam structure(s) contribute to a range of configuration options.

[0043] According to another aspect of the present invention, there is provided a cam system substantially as described above wherein adjustability of the cam structures' positions relative to each other in turn effects variation in the combined cam edge profile.

[0044] According to another aspect of the present invention, there is provided a cam system substantially as described above wherein the variation to the configuration of the cam edge profile in turn effects incremental variation in the translational movement of the cam follower and effect variation in the speed of operation of the mechanical function required.

[0045] According to another aspect of the present invention, there is provided a cam system substantially as described above wherein adjustability of the position of the side cam structure(s) relative to the central cam structure(s) is effected by use of at least one cam pivoting apparatus.

[0046] According to another aspect of the present invention, there is provided a cam system substantially as described above wherein the cam pivoting apparatus when in place enables the side cam structure(s) to freely pivot laterally to the central cam structure(s) to whatever position is required to effect the preferred combined edge profile and thus the variation in operation of the cam system and once the desired configuration is determined, the cam structures are interlocked via the cam locking apparatus.

[0047] According to another aspect of the present invention, there is provided a cam system substantially as described above wherein the operational speed variations available between the cam system when set at its lowest setting (smallest configuration) and its highest setting (largest configuration) with two side cam plates attached is approximately 200% (two hundred percent).

[0048] According to another aspect of the present invention, there is provided a cam system substantially as described above wherein the cam structure is associated with a travelling irrigator.

[0049] In preferred embodiments of the present invention the central cam structure comprises at least one central flat cam structure. For ease of use, the cam structures shall from hereon be referred to as cam plates. However, use of this term should not be seen as limiting the scope of this invention.

[0050] In one preferred embodiment, the central cam plate has a preferred edge profile as required to effect preferred translational motion via the follower to effect operation of a mechanical requirement. For example, in relation to the use of the invention with travelling irrigators, the translational motion effects the winding in of the wire rope of the irrigator.

[0051] In other embodiments however, the cam structure may be a face cam or drum cam, with an appropriate configuration and /or profile as required.

[0052] It must also be appreciated that where plate cams are employed with the invention that multiple central cam plates may be used. Therefore, in a further preferred embodiment, at least two central cam plates are employed. The at least two central cam plates are arranged substantially parallel to each other. However, the multiple cam plates are preferably distanced from each other. The distance between the central cam plates is such as to allow attachment of at least one side cam structure therewith.

[0053] Nevertheless, the distance between the central cam plates may be determined by any one or more of the depth dimensions of the at least one side cam structure, or by the configuration of either or both cam pivoting apparatus and cam locking apparatus used to maintain the central cam plates in a fixed relationship to each other.

[0054] For ease of use, the cam pivoting apparatus and the cam locking apparatus shall now be referred to as a cam pivot pin and a cam locking pin, respectively. However, use of these terms should not be seen as limiting the scope of this invention.

[0055] The central cam plate(s) may be configured to take any appropriate shape as required to effect the preferred edge profile required to effect the preferred translational motion via the follower.

[0056] In preferred embodiments of the present invention where the invention is described with relevance to plate cams, the side cam structure also consists of at least one flat side cam plate. The side cam plate also has a preferred edge profile that complements, but extends the edge profile of the central cam plate(s) as is required to effect a preferred variation in the translational motion achieved via the cam follower to effect the desired variation to the mechanical operation.

[0057] In other embodiments however, where the cam structure may be a face cam or drum cam, the configuration of the side cam structures would need to be adapted to enable the side cam structure not only to be attachable to the central cam structure(s), but also to be complementary to the required profile.

[0058] It should be appreciated that the present invention lends itself to use of more than one side cam plates with one or more central cam plates. The number and arrangement of the side cam plate(s) relative to the central cam plate(s) will thus determine desired variability in timing/speed of the translational motion of the cam follower to effect variability in the mechanical operation required.

[0059] The side cam plates are arranged relative to the central cam plate(s) so as to create a relatively seamless extension to the edge profile of the overall combined structure. In one embodiment of the present invention this is achieved by the side cam plate being positioned in between two adjacent central cam plates. In yet other embodiments, the side cam plate(s) may be configured to have a stepped configuration in a cross-sectional side view, such that the side plate includes an overlapping portion capable of overlapping a portion of a surface of a central cam plate. The overlapping complementary portion of the side plate may be the same depth as the central cam plate. Thus when the two plates are aligned the overall combined edge profile is different to the edge profile of the central or side cam plate alone, yet the configurations of the cam plates are such that the combined edge profile is substantially seamless.

[0060] The side cam plate(s) may be configured to take any appropriate shape as required to effect the preferred combined edge profile required to effect the preferred translational motion effected via the cam follower. Depending on the desired performance, one or more side plates may be attached to the central cam plate(s).

[0061] To maintain firm connection between either or both multiple central cam plates and attached side cam plates at least one cam locking pin is used to effect the plates in a fixed relationship to each other. There is preferably at least one additional locking pin for each additional plate. The locking pin is inserted to keep the cam plates in the preferred arrangement.

[0062] In order to interlock the plates, each plate includes at least one aperture capable of alignment with a complementary aperture on another plate. Thus when the locking pin is engaged with in-line apertures on two or more plates, the plates are fixed together firmly. It is important to effect firm interlocking not only given the torque effected via the central rotational cam shaft, but also because any sloppy movement of the cam plates relative to each other may negatively impact on the operation of the cam structure, as well as resulting in wear around the internal surface of the apertures which would further increase the likelihood of inter-plate movement. Further, burring or wearing of the apertures would also necessitate replacement of the cam plates more frequently.

[0063] The present invention preferably uses a tapered locking pin. The taper is set at 7° (degrees). This degree of tapering effects a very firm fit and maintains the plates in a tight relationship with each other. This is important to minimize movement of the plates relative to each other that might affect the functionality of the cam system, or cause damage to the plates. The cam plate apertures are also preferably tapered to 7° (degrees) to accept the pin. While other degrees of tapering may be preferred in some situations, any less than 7 degrees makes it extremely difficult to separate the plates after they have been locked. In order to complete the locking process, a threaded bolt is fixed to an underside surface of the cam plate(s) to complement a corresponding thread included on the tapered pin.

[0064] While one form of locking pin has been described in relation to the present invention, it should be appreciated that any other suitable locking means or a combination of locking means may be employed, or adapted for use with the cam system, without deviating from the scope of the invention. Accordingly, the locking pin may be configured to include a threaded, bayonet, or push fit locking pin.

[0065] Just as the apertures in the central and side cam plates facilitate interlocking of the plates, the same or additional apertures are used to effect adjustability of the cam plates' positions relative to each other and in turn effect variation in the combined cam edge profile.

[0066] Thus in preferred embodiments of the present invention, the cam system becomes adjustable via the use of complementarily positioned apertures on the cam plates. The positioning of the apertures on the cam plates, the distances between adjacent apertures and the ability to variably position the side cam plates with respect to the central cam plate(s) contribute to a range of configuration options. The various configurations in turn are able to effect incremental variation in the translational movement of the cam follower and effect variation in the speed of operation of the mechanical function required.

[0067] Thus, the adjustable cam allows an incremental increase in the power or speed effective of the cam, depending on the setting chosen for the arrangement of the central cam plate(s) and the additional adjustable side plates.

[0068] In order to more easily adjust the position of the side cam plate(s) relative to the central cam plate(s) the present invention preferably includes at least one cam pivot pin. As with the cam locking pin, there is preferably one cam pivot pin for each additional side cam plate. The cam pivot pin is inserted through complementarily positioned cam pivot apertures on each (side and central) cam plate. When the cam pivot apertures are aligned and the cam pivot pin is in place, the side plates are able to freely pivot laterally to the central cam plate(s) to whatever position is required to effect the preferred combined edge profile and thus the variation in operation of the cam system. Once the desired position of the one or more cam side plates is determined, the plates are all interlocked via the cam locking pin previously discussed.

[0069] The cam pivot pin is preferably retained in position via use of a cotter pin through an aperture at the base of the pivot pin. However, any other locking system that retains the pivot pin in place as required, may be used with this invention.

[0070] While a cam pivot pin is described with reference to the present invention, it should also be appreciated that other adjustment means may be employed, or adapted for use, with the invention.

[0071] The design of the present cam system is such that it enables adjustments to be made incrementally and with relative ease. Simply, the central cam plate(s) may be used alone. Alternatively, one or more side cam plates may be added to provide adjustability. Depending on what speeds are required, the cam locking pin(s) is removed, the side cam plate(s) pivoted to a preferred position equating to a preferred outcome, the cam apertures on the adjacent plates are realigned and the locking pin replaced. Such adjustment is therefore not time intensive, does not require complex additional pieces of machinery, specialist knowledge or tools and is an effective adjustment means.

[0072] The speed variations available when the different cam positions are set, may be better described as percentages for comparative purposes. For example, when a central cam plate is positioned relative to two side cam plates, the difference in operation between the cam system when set at its lowest setting (smallest configuration) with the two side cam plate(s) attached and its highest setting (largest configuration) with two side cam plates attached is approximately 200% (two hundred percent). Further, therefore, the difference in operation when including a single cam plate, or more cam side plates as opposed to a single central cam plate alone, may therefore be appreciated.

[0073] In the embodiment particularly described in this specification the number of adjustment apertures in the side cam plates—if spaced evenly—can also be shown as a percentage. For example, six apertures divided by 100 equates to 16.6%. Thus each aperture setting adjustment in relation to the side cam plates effects a comparable increase in the speed by 16.6%. This effect also is relevant for equally spaced holes in the central cam plate(s).

[0074] Therefore, a combination of cam adjustment apertures in both the central cam plate(s) and in the side plates, along with whether one or two side cam plates are used, provides a greater range of cam configuration/cam positions and hence a change in the profile distance and shape followed by the cam follower which in turn translates to a range of variations in speed by which, for example, a wire rope may be wound in and an irrigator travels across a surface.

[0075] The combined cam plate configurations and hence settings as can be appreciated are extensive, determined further by either or both the number of cam adjustment apertures and the spacing between the cam adjustment apertures.

[0076] As can be appreciated the adjustments to the cam system operation obtained through the numerous alternative positions of the side cam plates relative to the central cam plate(s) of the present invention and the associated range of speed options, provides an advantage over prior art cam systems used particularly with travelling irrigators, as well as in other machinery which could benefit from the incorporation of an adjustable cam system.

[0077] As mentioned previously, the cam has been designed for use on a travelling irrigator as used on dairy farms, for example. Such irrigators typically have a fixed (non-adjustable) cam. The travelling irrigators are commonly used on farms for transferring the substantially liquid wastes from a dairy (milking) shed over neighboring paddocks in a manner that directly returns raw nutrients to the land. In other applications, any suitably fluid substance may be sprayed, or aerated, as required for the particular situation.

[0078] The cam associated with a travelling irrigator is typically in the form of a plate cam. In such machinery the cam system provides power during revolution of the cam plate as the irrigation boom revolves. The rotational movement of the cam plate is translated through the cam follower to effect the winding in of the wire rope of the irrigator. In such applications the cam plate is fixed to a preferable size and shape. Such fixed structural features operate against the cam dimensions being adjustable and thus limit adjustability of the translational motion effected through the cam follower and hence restricts any variability of the speed of the preferred operation.

[0079] However, having a simple variable speed cam system for use with travelling irrigators would benefit the operation of the irrigation process by allowing for either a speeding up of the operation or slowing it down, depending on the size of the area being irrigated and/or the quantity of fluid being delivered by the irrigator. However, at times it is useful to have the standard cam plate to effect the standard operation of the machine.

[0080] As can be appreciated variations to and from the above described embodiments may be made without deviating from the scope of the present invention.

[0081] It should further be appreciated a variety of different embodiments, uses, and applications of the present invention exist, even within the ambit of the above described cam system. A specific embodiment for the present invention will now be given by way of example only, to help better describe and define the present invention. However, describing one embodiment should not be seen as limiting the scope of this invention.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0082] Further aspects of the present invention will become apparent from the following description, given by way of example only and with reference to the accompanying drawings in which:

[0083]FIG. 1 is a perspective view of the adjustable cam system in accordance with one preferred embodiment of the present invention;

[0084]FIG. 2 is a cross-sectional view of the adjustable cam system of FIG. 1 in accordance with one preferred embodiment of the present invention;

[0085]FIG. 3 is a top plan view of the adjustable cam system of FIGS. 1 and 2 showing available adjustment positions, in accordance with one preferred embodiment of the present invention; and

[0086]FIG. 4 is a top plan view of the adjustable cam system of FIGS. 1 and 2 showing further available adjustment positions to those of FIG. 3, in accordance with one preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0087] With reference to the diagrams (FIGS. 1 to 4) by way of example only, there is provided a cam system (generally indicated by arrow 1). While the cam system is described and referenced for use with travelling irrigators, it should be appreciated this invention may have application outside of this field.

[0088] The cam system includes at least two cam structures (illustrated in FIGS. 1 to 4), a cam follower (not shown) capable of following a preferred profile effected by the configuration of at least one of the cam structures, and a substantially central cam shaft (also not shown).

[0089] The cam structures are adapted at 8 to have a circumferential edge profile along which the follower travels. The central cam plate(s) may be configured to take any appropriate shape as required to effect the preferred edge profile required to effect the preferred translational motion via the follower.

[0090] The cam structures comprises at least one central cam structure 2 and at least one side cam structure 3 and 3 a. The central cam structure is adapted at 9 to receive the cam shaft. The central cam plate(s) may be configured to take any appropriate shape as required to effect the preferred edge profile required to effect the preferred translational motion via the follower. The central cam structure(s) or central cam plate(s) 2 are further adapted to receive at least one of the side cam structure(s) or plate(s) 3 and 3 a.

[0091] The central cam structure illustrated in FIGS. 1 and 2 particularly, consists of two substantially flat central cam plates arranged substantially parallel to each other, but distanced from each other. The distance between the central cam plates is such as to allow attachment of at least one side cam plate.

[0092] The distance between the central cam plates may be determined by any one or more of the depth dimensions of the side cam plate, or by the configuration of either or both a cam pivot pin 4 and a cam locking pin 7 used to maintain the central cam plates alone, or in conjunction with the side plates, in a fixed relationship to each other. There is preferably at least one additional locking pin for each additional plate.

[0093] In order to interlock the plates, each central plate includes at least one aperture 6 capable of alignment with a complementary aperture (6 a) on the side cam plate(s). Thus when the locking pin is engaged with in-line apertures on two or more plates, the plates are fixed together firmly.

[0094] The position of the side cam plates can however be varied with respect to the central cam plate to effect a change in the profile of the central cam plate when viewed alone, and in turn change the overall profile followed by the cam follower during rotation of the cam shaft and the cam plates(s) related thereto.

[0095] The side cam plates are arranged relative to the central cam plate(s) so as to create a relatively seamless extension to the edge profile of the overall combined structure. In one embodiment of the present invention this is achieved by the side cam plate being positioned in between two adjacent central cam plates as shown in the attached figures. In yet other embodiments (not shown), the side cam plate(s) may be configured to have a stepped configuration in a cross-sectional side view, such that the side plate includes an overlapping portion capable of overlapping a portion of a surface of a central cam plate and a complementary portion of the same depth as the central cam plate. Thus when the two plates are aligned the overall combined edge profile is different to the edge profile of the central or side cam plate alone, yet the configurations of the cam plates are such that the combined edge profile is substantially seamless. Depending on the desired performance, one or more side plates may be attached to the central cam plate(s).

[0096] Just as the apertures in the central and side cam plates facilitate interlocking of the plates, the same or additional apertures are used to effect adjustability of the cam plates' positions relative to each other and in turn effect variation in the combined cam edge profile.

[0097] The various configurations are illustrated particularly in FIGS. 3 and 4 to show how incremental variation in the size of the cam plate system and the incremental increase in the overall distance of the edge profile of the cam plates traveled by the cam follower can be achieved. Thus, the adjustable cam allows an incremental increase in the power generated by or speed of operation of the cam, depending on the setting chosen for the arrangement of the central cam plate(s) and the additional adjustable side plates.

[0098] To adjust the position of the side cam plate(s) relative to the central cam plate(s) at least one cam pivot pin 4 is used. As with the cam locking pin, there is preferably one cam pivot pin for each additional side cam plate. The cam pivot pin is inserted through complementarily positioned cam pivot apertures 5 on each cam plate. When the cam pivot apertures are aligned and the cam pivot pin is in place, the side plates are able to freely pivot laterally to the central cam plate(s) to whatever position is required to effect the preferred combined edge profile and thus the variation in operation of the cam system. Once the desired position of the one or more cam side plates is determined, the plates are all interlocked via the cam locking pin 7. Simply, the central cam plate(s) may be used alone, or one or more side cam plates may be added to provide adjustability.

[0099] As can be appreciated variations to and from the above described embodiments may be made without deviating from the scope of the present invention.

[0100] It should also be understood that the term “comprise” where used herein is not to be considered to be used in a limiting sense. Accordingly, ‘comprise’ does not represent nor define an exclusive set of items, but includes the possibility of other components and items being added to the list.

[0101] This specification is also based on the understanding of the inventor regarding the prior art. The prior art description should not be regarded as being an authoritative disclosure of the true state of the prior art but rather as referring to considerations in and brought to the mind and attention of the inventor when developing this invention.

[0102] Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope thereof, as defined in the appended claims. 

What is claimed is:
 1. A cam system comprising: at least two cam structures, the at least two cam structures being adapted to co-operate with a cam follower capable of following a preferred profile effected by the configuration of at least one of the at least two cam structures and a movable cam shaft, the at least two cam structures including: at least one central cam structure and at least one side cam structure, the at least one central cam structure being adapted to receive the movable cam shaft and operate therewith, the at least one central cam structure further adapted to receive the at least one side cam structure, the at least one side cam structure being adapted to be variably positioned with respect to the at least one central cam structure thereby effecting a change in the profile of the at least one central cam structure alone and in turn effecting a change in the overall profile followed by the cam follower during movement of the cam shaft and the at least two cam structure(s) associated therewith; wherein the change in profile effected by the positional configuration of the at least one side cam structure relative to the at least one central cam structure enabling variation in the translational motion to the cam follower during movement of the movable cam shaft and the at least two cam structures being movable therewith and effecting in turn a variation in either or both speed and power of operation of a preferred movement relevant to a mechanical requirement.
 2. A cam system as claimed in claim 1 wherein the cam structure(s) comprises any one of a plate cam, a face cam, a drum cam relevant to the application with which the cam system is used.
 3. A cam system as claimed in claim 1 wherein the follower comprises any one of a knife-edge follower, a roller follower.
 4. A cam system as claimed in claim 1 wherein either or both the central cam structure and the side cam structure take any appropriate shape as required to effect a preferred edge profile as required to effect preferred translational motion via the follower resulting in the preferred operation of the mechanical requirement.
 5. A cam system as claimed in claim 1 wherein the number and arrangement of the side cam structure(s) relative to the central cam structure(s) determine desired variability in either or both the timing and the speed of the translational motion of the follower to effect the mechanical operation required.
 6. A cam system as claimed in claim 5 wherein either or both the central cam structure(s) and the side cam structure(s) are maintained in a fixed relationship to each other during operation of the cam system by either or both cam pivoting apparatus and cam locking apparatus.
 7. A cam system as claimed in claim 6 wherein to maintain the cam structures in a fixed relationship to each other, each structure includes at least one aperture capable of alignment with a complementary aperture on another structure, through which the cam locking apparatus is engaged.
 8. A cam system as claimed in claim 7 wherein the cam locking apparatus is adapted to complement the configuration of the apertures and includes any one or more of a tapered, threaded, bayonet, push fit locking pin.
 9. A cam system as claimed in claim 6 wherein prior to effecting the cam structures in a fixed relationship to each other, the side cam structure is adjustable positionally with respect to the central cam structure to effect a range of central cam: side cam configuration options.
 10. A cam system as claimed in claim 9 wherein the range of configuration options is achievable via the use of complementarily positioned apertures on each cam structure, the positioning of the apertures on each cam structure and the distances between adjacent apertures.
 11. A cam system as claimed in claim 10 wherein variable positioning of the position of either or both the central and side cam structures relative to each other in turn effects variation in the profile of the combined cam structure.
 12. A cam system as claimed in claim 11 wherein the variation in the profile of the combined cam structure in turn varies the translational movement of a cam follower in contact therewith and effects a variation in the speed or power of operation of the associated mechanical function required.
 13. A cam system as claimed in claim 11 wherein the side cam structure(s) and/or the central cam structure(s) are adapted to be variably positioned by use of at least one cam pivoting apparatus.
 14. A cam system as claimed in claim 13 wherein the cam pivoting apparatus when in place enables the side cam structure(s) to freely pivot relative to the central cam structure(s) to whatever position is required to effect the preferred combined edge profile and the cam structures are maintained in that configuration via the cam locking apparatus.
 15. A cam system as claimed in claim 14 wherein where multiple central cam structures are employable, the central cam structures are arranged substantially parallel to, but distanced from each other.
 16. A cam system as claimed in claim 15 wherein the distance between the central cam structures is adapted for attachment of at least one side cam structure.
 17. A cam system as claimed in claim 16 wherein the side cam structure(s) are arranged relative to the central cam structure(s) as a substantially seamless extension to the edge profile of the overall combined structure.
 18. A cam system as claimed in claim 16 wherein the side cam structure(s) includes a stepped configuration in cross-section adapted to overlap a portion of a surface of a central cam structure but of a depth such that the combined edge profile is substantially seamless yet the combined edge profile is different to the edge profile of the central or side cam structure alone.
 19. A cam system as claimed in claim 14 wherein the cam locking apparatus is a tapered locking pin.
 20. A cam system as claimed in claim 19 wherein the taper of the locking pin is set at 7° (degrees).
 21. A cam system as claimed in claim 20 wherein the tapered locking pin engages with apertures on the cam structures which are also tapered to 7° (degrees) to accept the pin.
 22. A cam system as claimed in claim 21 wherein in the locking pin includes a threaded portion at its outer distal end adapted to engage with complementarily configured threaded bolt.
 23. A cam system as claimed in claim 14 wherein the cam structures include apertures located at predetermined distances which are adjustment apertures to variably position the side cam structures with respect to the central cam structure(s) through a range of interconnected configuration options.
 24. A cam system as claimed in claim 13 wherein the cam pivoting apparatus is a cam pivot pin.
 25. A cam system as claimed in claim 24 wherein at least one cam pivot pin is provided for each additional side cam structure interconnected with one or more central cam structures.
 26. A cam system as claimed in claim 25 wherein a cam pivot pin is retained in position via use of locking system, including a cotter pin through an aperture at the base of the pivot pin.
 27. A cam system as claimed in claim 12 wherein the operational speed variations available when the cam system is set at its highest setting with two side cam structures attached (to form its largest configuration) compared with its lowest setting (smallest configuration), is approximately 200% (two hundred percent).
 28. A cam system as claimed in claim 23 wherein adjustment apertures in each of two side cam structures number six, each aperture setting adjustment in relation to the side cam structures effects a comparable incremental increase in the speed generation resulting from the translational motion of the cam follower by 16.6%.
 29. A cam system as claimed in claim 28 wherein the incremental speed effect is relevant for equally spaced holes in the central cam structure(s).
 30. A cam system as claimed in claim 1 wherein the cam structure is associated with a traveling irrigator.
 31. A cam system as claimed in claim 30 wherein the cam structure(s) having a preferred profile in operation effects preferred translational motion via the cam follower to wind in the wire rope of the travelling irrigator at a preferred speed, thereby effecting movement of the irrigator across a surface at a preferred speed.
 32. A traveling irrigator incorporating a cam system as claimed in claim
 1. 33. A method of manufacturing a cam system, the cam system comprising at least two cam structures, the at least two cam structures being adapted to co-operate with a cam follower capable of following a preferred profile effected by the configuration of at least one of the at least two cam structures and a movable cam shaft, the at least two cam structures comprising at least one central cam structure and at least one side cam structure, the at least one central cam structure being adapted to receive the movable cam shaft and operate therewith, the at least one central cam structure further adapted to receive the at least one side cam structure, the at least one side cam structure being adapted to be variably positioned with respect to the at least one central cam structure thereby effecting a change in the profile of the at least one central cam structure alone and in turn effecting a change in the overall profile followed by the cam follower during movement of the cam shaft and the at least two cam structure(s) associated therewith, wherein the change in profile effected by the positional configuration of the at least one side cam structure relative to the at least one central cam structure enabling variation in the translational motion to the cam follower during movement of the movable cam shaft and the at least two cam structures being movable therewith and effecting in turn a variation in either or both speed and power of operation of a preferred movement relevant to a mechanical requirement, the method including the steps of: a) manufacturing at least one central cam structure and at least one side cam structure each having a preferred profile for use separately or combined; b) providing, in the central cam structure, an aperture adapted to receive a movable cam shaft; c) providing the central cam structure(s) and the side cam structure(s) with adjustment apertures enabling repositioning of the side cam structure(s) relative to the central cam structure(s); d) manufacturing pivoting apparatus to engage with the cam structures to enable the cam structures to pivot relative to each other; e) manufacturing locking apparatus to maintain the cam structures in a preferred fixed relationship having a substantially seamless yet combined edge profile different to the edge profile of the central or side cam structure alone; and f) providing the edge/face profile of the cam structures singularly or combined being adapted to co-operate with a cam follower.
 34. A method of varying the speed of operation of a cam system, the cam system comprising at least two cam structures, the at least two cam structures being adapted to co-operate with a cam follower capable of following a preferred profile effected by the configuration of at least one of the at least two cam structures and a movable cam shaft, the at least two cam structures comprising at least one central cam structure and at least one side cam structure, the cam structures including adjustment apertures located at predetermined distances which in conjunction with pivoting apparatus variably positions the side cam structures with respect to the central cam structure(s) through a range of interconnected configuration options, and locking apertures which in conjunction with locking apparatus maintains the cam structures in a preferred interconnected configuration, the central cam structure being adapted to receive the cam shaft and move therewith, the central cam structure further adapted to receive the at least one side cam structure, the side cam structure being adapted to be positionally varied with respect to the central cam structure via the pivoting apparatus thereby effecting a change in the profile of the central cam structure alone, and in turn effecting a change in the overall profile followed by the cam follower during movement of the cam shaft and the cam structure(s) related thereto, wherein the change in profile effected by the positional configuration of the side cam structure effecting variable translational motion to the cam follower during movement of the cam shaft and cam structures associated therewith and effecting in turn a variation in either or both power and speed of operation of a preferred a mechanical requirement, the method including the steps of: a) pivoting, via the pivoting apparatus, the side cam structure(s) relative to the central cam structure(s) between smallest and greatest profile configuration options to achieve the preferred profile configuration relevant to the preferred speed and/or power of operation required; b) aligning adjustment apertures of the side cam structure(s) with the adjustment apertures of the central cam structure; and c) inserting cam locking apparatus through aligned cam locking apertures to effect a fixed substantially seamless yet combined edge profile different to the edge profile of the central or side cam structure alone.
 35. An existing cam system capable of being modified to effect a cam system as claimed in claim
 1. 36. An adjustable cam system as claimed in claim 1 for use with a traveling irrigator.
 37. A cam side structure for use with a cam system as claimed in claim
 1. 38. A cam central structure for use with a cam system as claimed in claim
 1. 